Kohn Anomalies and Electron‐Phonon Coupling in Carbon Nanotubes

Kohn anomalies are distinct features of the phonon dispersion in metallic systems, associated to the presence of a Fermi surface. Graphene is a model system to understand the physical properties of carbon nanotubes. Two Kohn anomalies are present in the phonon dispersion of graphene and their slope is proportional to the square of the electron‐phonon coupling. Kohn anomalies are enhanced in metallic nanotubes due to their reduced dimensionality and absent for semiconducting. The electron‐phonon coupling for nanotubes of arbitrary chirality and diameter can be obtained from graphite.